Mobile apparatus, such as a hospital gurney and a mobile intravenous (IV) infusion stand, must sometimes be moved in tandem. Such a situation occurs when a patient who is connected to an IV apparatus must be transported by a gurney or wheelchair. It is extremely awkward for one person to simultaneously move both mobile apparatus.
Such mobile apparatus may be simultaneously moved more easily if interconnected by a hitch device. However, the hitch device must impart stability to the interconnected apparatus upon movement. For example, the hitch device must prevent a tall, sometimes top-heavy apparatus, such as a mobile IV stand, from bouncing and tipping over during transport, particularly when bumps in a floor are encountered.
Prior hitch devices do not permit a pulled apparatus to closely track the path of the pulling apparatus. This lack of tracking requires a larger space to traverse corners and makes it more difficult to control the movement of both apparatus. Although this problem may be partially solved by providing a hitch which maintains the pulled apparatus to one side of the pulling device, such an arrangement only makes it easier to traverse corners in one direction (opposite the side of the pulled apparatus). Moreover, these devices create an additional problem, namely, the pulling and pulled apparatus require a wider path. This is particularly disadvantageous in crowded areas such as hospital corridors. Further, when traversing a corner, the pulled apparatus will not ride smoothly and may even tip over (especially if the pulled apparatus is a top-heavy object like a mobile IV infusion stand) in response to the abrupt change in direction. However, the change in direction will not be so abrupt and the pulled apparatus will ride more smoothly if the hitch device connecting the pulling and pulled apparatus will flex laterally. It would also be advantageous for the hitch device to automatically realign the pulled and pulling apparatus to an axial position after traversing a corner to provide a minimum path width for the tandem apparatus.
The following patents disclose hitch devices that permit lateral movement of one of the interconnected mobile apparatus: Garrison, U.S. Pat. No. 4,444,409 (issued Apr. 24, 1984) (FIGS. 2 and 3); Fisher. U.S. Pat. No. 4,588,199 (issued May 13, 1986) (FIG. 1, lateral movement possible around ball element 12); Clark, U.S. Pat. No. 4,596,399 (issued Jun. 24, 1986) (lateral movement possible by pivoting around kingpins 33, column 4, lines 17-22 and FIGS. 5-7); Fromberg, U.S. Pat. No. 4,711,461 (issued Dec. 8, 1987) (lateral movement possible by rotation around axis b, FIG. 2). However, none of these devices has resilient means for restoring the hitch device to its original configuration after traversing a corner. Further, none of these hitch devices importantly restrict vertical movement (bouncing) of a lightweight interconnected apparatus.
Kudriavetz, U.S. Pat. No. 3,224,224 (issued Jun. 7, 1963), discloses a flexible coupling that has torsional resilience (FIG. 2 and col. 1, lines 37-42). Although it is known to use the device disclosed in Kudriavetz to interconnect two mobile apparatus, the device disclosed in Kudriavetz does not restrict vertical movement (bouncing) of a lightweight interconnected apparatus.
Kahlert, German Patent No. 235,201, discloses a coupling device which includes a spring. IV pole coupling devices that somewhat restrict vertical movement of an IV pole are disclosed in representative U.S. Pat. Nos. 4,511,158 and 4,572,536.